linux/Documentation/cgroups
Aristeu Rozanski bd2953ebbb devcg: propagate local changes down the hierarchy
This patch makes exception changes to propagate down in hierarchy respecting
when possible local exceptions.

New exceptions allowing additional access to devices won't be propagated, but
it'll be possible to add an exception to access all of part of the newly
allowed device(s).

New exceptions disallowing access to devices will be propagated down and the
local group's exceptions will be revalidated for the new situation.
Example:
      A
     / \
        B

    group        behavior          exceptions
    A            allow             "b 8:* rwm", "c 116:1 rw"
    B            deny              "c 1:3 rwm", "c 116:2 rwm", "b 3:* rwm"

If a new exception is added to group A:
	# echo "c 116:* r" > A/devices.deny
it'll propagate down and after revalidating B's local exceptions, the exception
"c 116:2 rwm" will be removed.

In case parent's exceptions change and local exceptions are not allowed anymore,
they'll be deleted.

v7:
- do not allow behavior change when the cgroup has children
- update documentation

v6: fixed issues pointed by Serge Hallyn
- only copy parent's exceptions while propagating behavior if the local
  behavior is different
- while propagating exceptions, do not clear and copy parent's: it'd be against
  the premise we don't propagate access to more devices

v5: fixed issues pointed by Serge Hallyn
- updated documentation
- not propagating when an exception is written to devices.allow
- when propagating a new behavior, clean the local exceptions list if they're
  for a different behavior

v4: fixed issues pointed by Tejun Heo
- separated function to walk the tree and collect valid propagation targets

v3: fixed issues pointed by Tejun Heo
- update documentation
- move css_online/css_offline changes to a new patch
- use cgroup_for_each_descendant_pre() instead of own descendant walk
- move exception_copy rework to a separared patch
- move exception_clean rework to a separated patch

v2: fixed issues pointed by Tejun Heo
- instead of keeping the local settings that won't apply anymore, remove them

Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2013-03-20 07:50:21 -07:00
..
00-INDEX cgroups: move cgroup_event_listener.c to tools/cgroup 2013-01-07 09:41:28 -08:00
blkio-controller.txt Merge branch 'for-3.9/core' of git://git.kernel.dk/linux-block 2013-02-28 12:52:24 -08:00
cgroups.txt cgroup: hold cgroup_mutex before calling css_offline() 2013-03-12 15:35:59 -07:00
cpuacct.txt Documentation: fix echo command in cgroups/cpuacct.txt 2011-07-23 10:58:08 -07:00
cpusets.txt cpuset: use N_MEMORY instead N_HIGH_MEMORY 2012-12-12 17:38:32 -08:00
devices.txt devcg: propagate local changes down the hierarchy 2013-03-20 07:50:21 -07:00
freezer-subsystem.txt cgroup_freezer: implement proper hierarchy support 2012-11-09 10:52:30 -08:00
hugetlb.txt hugetlb/cgroup: add HugeTLB controller documentation 2012-07-31 18:42:41 -07:00
memcg_test.txt cgroups: move cgroup_event_listener.c to tools/cgroup 2013-01-07 09:41:28 -08:00
memory.txt kmem: add slab-specific documentation about the kmem controller 2012-12-18 15:02:15 -08:00
net_prio.txt netprio_cgroup: allow nesting and inherit config on cgroup creation 2012-11-22 07:32:47 -08:00
resource_counter.txt res_counter: return amount of charges after res_counter_uncharge() 2012-12-18 15:02:12 -08:00